Thermal behaviour of laminated bamboo structures under fire conditions

摘要

A series of experiments have been conducted to measure the in-depth heating of laminated bamboo samples subjected to heat fluxes of 5, 10, 30, and 60 kW/m(2), either perpendicular or parallel to the grain. These heat fluxes were chosen to induce different phenomena within the material-from inert heating to moisture evaporation, pyrolysis, oxidation, and flaming-so that the effects of these can be isolated and evaluated separately by simple heat-transfer models. Moisture migration along the fibres becomes a critical factor when bamboo is heated parallel to the grain, resulting in increased convective heat transfer to deeper parts of the material and an accumulation of moisture in depth that accentuates the endothermic plateau in the temperature profiles around 100 degrees C. Average charring rates for 60 minutes of exposure under 60 kW/m(2) were 0.74 and 0.70 mm/min for perpendicular and parallel heating, respectively. The thickness of the heated layer was much larger for parallel heating due to moisture migration, which is less significant perpendicular to the grain. Inert heat diffusion is a good approximation at heat fluxes of 5 and 10 kW/m(2), but exothermic oxidation reactions become critical above 400 degrees C and must be included in future models.